lam1 = 1540;  
de1 = [1.095, 1.092, 1.090, 1.093, 1.094, 1.091];  
c = 4200;  
x =sin(pi/4) *[0.6, 1.2, 1.8, 2.4, 3.0, 3.6];  
kap1 = c * de1 / lam1;  
y = kap1;  
xc = [0.3, 0.4, 0.5,0.6, 0.7];  
yc = spline(x, y, xc,); 
disp(yc);